Log when CNB_LAUNCH_UMASK is incorrect

Pass a logger down to the process launcher and log when setting
the umaks is incorrect and continue.

Author: AidanDelaney

cmd/launcher/cli/launcher.go

@@ -49,6 +49,7 @@ func RunLaunch() error {
 		ExecD:              launch.NewExecDRunner(),
 		Shell:              launch.DefaultShell,
 		Setenv:             os.Setenv,
+		Logger:             cmd.DefaultLogger,
 	}
 
 	if err := launcher.Launch(os.Args[0], os.Args[1:]); err != nil {

launch/launcher.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/buildpacks/lifecycle/api"
 	"github.com/buildpacks/lifecycle/env"
+	"github.com/buildpacks/lifecycle/log"
 )
 
 var (
@@ -26,6 +27,7 @@ type Launcher struct {
 	ExecD              ExecD
 	Shell              Shell
 	LayersDir          string
+	Logger             *log.DefaultLogger
 	PlatformAPI        *api.Version
 	Processes          []Process
 	Setenv             func(string, string) error
@@ -70,8 +72,8 @@ func (l *Launcher) LaunchProcess(self string, proc Process) error {
 	proc.WorkingDirectory = getProcessWorkingDirectory(proc, l.AppDir)
 
 	err := SetUmask(l.Env)
-	if err != nil {
-		return errors.Wrap(err, "umask")
+	if err != nil && l.Logger != nil {
+		l.Logger.Errorf("invalid umask: %s", err)
 	}
 
 	if proc.Direct {

launch/launcher_test.go

@@ -125,6 +125,7 @@ func testLauncher(t *testing.T, when spec.G, it spec.S) {
 				process.Command = launch.NewRawCommand([]string{"sh"})
 
 				mockEnv.EXPECT().Get("PATH").Return("some-path").AnyTimes()
+				mockEnv.EXPECT().Get("UMASK").Return("").AnyTimes()
 				launcher.Setenv = func(k string, v string) error {
 					if k == "PATH" {
 						setPath = v

launch/umask_unix.go

@@ -3,23 +3,28 @@
 package launch
 
 import (
+	"fmt"
 	"strconv"
 	"syscall"
 
 	"github.com/pkg/errors"
 )
 
+const (
+	umaskEnvVar = "CNB_LAUNCH_UMASK"
+)
+
 // SetUmask on unix systems from the value in the `UMASK` environment variable
 func SetUmask(env Env) error {
 	return SetUmaskWith(env, syscall.Umask)
 }
 
 // SetUmaskWith the injected function umaskFn
 func SetUmaskWith(env Env, umaskFn func(int) int) error {
-	if umask := env.Get("UMASK"); umask != "" {
+	if umask := env.Get(umaskEnvVar); umask != "" {
 		u, err := strconv.ParseInt(umask, 8, 0)
 		if err != nil {
-			return errors.Wrap(err, "invalid umask value")
+			return errors.Wrap(err, fmt.Sprintf("invalid umask value %s", umask))
 		}
 		umaskFn(int(u))
 	}